Casement Windows

What is a Casement Window?

Top hung casement windowsA casement window is probably what most people think of first if you ask them about new or replacement windows.

Casement windows can be seen in properties of all ages and design styles because they are so versatile when it comes to where they can be used and the different design combinations available.

It’s the part of the window that opens and closes that gives this design the name. The opening section, or casement, can be hinged at the top, bottom or side:

  • Top hinged are known as Awning windows (seen as top-lights in a lot of installations)
  • Side hinged are known simply as Casement windows
  • Bottom hung styles are known as Hopper windows

This type of window can be manufactured from wood, aluminium or uPVC or PVCu (Some older properties may even still have galvanised steel frames).

What are the features of casement windows?

These days, unless there is an overriding reason not to do so, double glazed casement windows would be fitted as the minimum standard and modern double glazing comes with a number of valuable features.

Energy Efficiency

Each window unit will either have an energy efficiency rating from British Standards Institution (BSI Kitemark) or the British Fenestration Rating Council (BFRC).

Generally, the rating will run from A to G. A, or even A++.  The most energy efficient is A++ and C is the minimum grade to comply with UK building regulations (with some exceptions).

With the BFRC you also get a colour code that runs from Purple (A++) to Amber (E).

Sound Proofing

Double glazed windows help to reduce noise pollution. The insulating gap between the panes helps to deaden sound transfer and so the interior of your home will suffer less from noise coming in from the outside. This feature also lets less noise out of your home.

With an overall thickness of 28mm, a modern double glazed 4/20/4 unit (4mm thick glass with 20mm gap) can lower the sound levels by up to 30 decibels.

An acoustic laminate of 6/16/6.8A can raise that up to an incredible 37 decibel reduction in noise. That is something like going from a busy high street to a library in terms of the drop in noise levels.


Windows can be a vulnerability for a burglar or intruder to take advantage of, so having good levels of security is important.

Go for locks that engage in multiple points around the frame and make sure there are internal window beads, these are the thin strips that hold the glass into the frame.

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What are the options for casement windows?

The quality of the frames and the glazing are the 2 key areas for any window and if you are opting for casement windows then it will pay dividends in the long term to get the best quality for your budget.

Multi-chamber frames

Chambered frames

Unlike timber frames, which are solid, aluminium and uPVC should have multi-chamber frames. You can get up to 5 chambers for the moving casement and 6 for the window frame.

Aluminium casement window frames need to have a thermal-break built into the unit because aluminium is a good thermal conductor. This is an internal feature that effectively thermally isolates the inside of the window from the outside.

PVCu window frames can benefit from internal galvanised steel reinforcing – especially useful for wide span frames.

Colour options

window colour swatch

Timber casement windows can be painted or stained to the colour or shade of your choice. Aluminium windows come with powder coated paint surfaces applied in the factory.

The choice is huge, with some suppliers offering up to 200 different shades. You can also opt for 2-tone, which has 1 colour outside and another inside. There are also options for aluminium clad windows.

uPVC can usually be found in 12 to 15 different colours and also has two-tone options with 1 colour inside and another outside. Both aluminium and uPVC offer timber effect or wood-grain effect finished surfaces.
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Mahogany casement windowsCasement windows can be made from wood, aluminium or uPVC (PVCu). Wood is a good natural insulator and can be painted any colour.

Aluminium is strong, lightweight and comes in slim-line profiles with over 100 colours. The lightness of aluminium combined with high structural strength allows for use in very large window frames.

uPVC is very versatile, also lightweight and very easy to look after. It’s also long lasting, non-reactive to a lot of air pollutants and very cost effective to use for casement window frames.

Nether aluminium nor uPVC need to be painted as the colour is factory applied and does not peel, fade or crack over time.



Click to view larger image

Single glazing is not advised. Double and triple glazed sealed units give the unit the majority of its energy efficiency. The glass itself is usually made from 2 x 4mm thick panes with up to a 20mm gap between them (4/20/4).

The gap can either be a vacuum or filled with an inert gas such as Argon to further improve the insulation properties of the window.

Glass comes with clear, patterned, frosted, leaded or coloured options.

Opening sections

Window openersIt is common practice for suppliers to add a charge for each window section that opens. Whether or not you are on a tight budget, this is a point well worth noting.

The fact that casement windows can open left, right, top or bottom makes for a virtually limitless number of available combinations.

One of the best ways to guide you in choosing which one should open to consider how the window will be used once fitted. For example, in a lounge area, openers may not be so important to have as they would be in a kitchen area.

Trickle vents

trickle vent cutawayThese are sometime overlooked, but play an important part in reducing or eliminating condensation in a well-insulated home.

These vents are built into the frame and allow controlled, draught free ventilation into and out of the room.

An average family of 4 can generate almost 16 litres (3.5 gallons) of water vapour per day. All that moisture that can end up as condensation if there is no proper ventilation, subsequently leading to mold and mildew.
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How much do casement windows cost?

Prices for casement windows are going to be driven by 4 or 5 major factors such as:

  1. Size of order – the “average cost per window” should be less if you are buying several at a time.
  2. Material used – timber, aluminium and uPVC have different pricing structures.
  3. Energy rating – A++ rated windows will be pricier than those with lower performance ratings.
  4. Optional extras – coloured / wood-grain uPVC or aluminium. Patterned or special glazing (leaded)
  5. Fitting cost – this is a big variable, but more labour = more cost.

You may also be changing your front and back door at the same time, if so, you should budget for around £500 to £600 for a uPVC door and £800 to £1,000 for a composite door fitted.

The cost to fit the average 4 bed detached house with around 10 or 12 windows of varying sizes is likely to be around £5,000 for uPVC, £7,000 for top quality timber windows and £7,000 for aluminium.

Casement window price guide

Number of units uPVC frames Aluminium frames Hardwood Timber frames
up to 4  £1,500 – £2,000 £2,300 – £2500 £2,000 – £2,500
up to 8  £3,500 – £4,000 £4,000 -£4,500 £4,000 -£5,000
up to 10  £4,000 – £4,500 £5,500 – £6,500 £5,500 – £6,000
up to 12  £4,500 – £6,000 £6,500 – £8,000 £6,000 – £7,000

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Some Frequently Asked questions

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How long does it take to fit a house with casement windows?

Obviously the amount of time the installer takes to do the work will vary somewhat, but you could reasonably expect it to take 3 t0 5 days to double glaze a 3 bed-semi.

How long does it take to deliver my new windows?

Timber, Aluminium and uPVC will all have different lead times – the time from order to delivery. You should find that the shortest lead times will be around 4 to 6 weeks for supply & fit.

You can find much shorter delivery times for supply only uPVC windows.

Are casement windows guaranteed?

Yes.  Both manufacturers and installers will offer guarantees on products and the installation work.

Can I have one colour on the outside of my window and a different colour inside?

Yes you can. Both aluminium and uPVC casement windows have the option to use 2 colours. Of course, timber can be painted to the colour of your choice.

More Window designs

More Window DesignsIf you are not sure that casement windows are suited to your home, then why not review these other designs to see if they are more to your liking:

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Have your windows fitted by professionals – look for these trade accreditations.

  • GGF